Posted
by
ScuttleMonkey
on Monday May 25, 2009 @05:18PM
from the please-include-armament-instructions dept.

Shojun writes "I am very interested in building my own UAV. Not just one that can fly around happily, but one that I can program to say, take photos every second as it does a barrel roll under a bus (ok, that part may be a pipe dream). I have enough embedded programming experience — it's the hardware which I'm uncertain about. I can go the kit way, and then build the remaining stuff, or get some Dollar Tree Foam boards and build it all. I'm in favor of ease, however. Once the plane is built, buying a dev board seems like a possibility, but I wonder whether it's overkill. Alternatively, if there was a How-to-build example on the net for such an activity that I could adapt, to the degree that I could then program in even completely hardcoded flight instructions, I can certainly take it from there. Thoughts? Has anyone here tried something like this before?"

The building of an autonomous flying craft has been the subject of student competition for quite a while, but the focus has generally been on helicopters, simply because you can get them to stand still... doing a good inertial autopilot on an airplane is significantly more challenging.

The last time some of my friends tried doing an automatic control system, the plane turned straight toward the flight line and tried to kill us all!

Unless you have extensive experience designing them, I would recommend going with a kit plane for hardware rather than trying to build one from scratch out of foam boards. The reason for this is that you will start out with a design you know is flyable and has the stability properties you want. One of the classic errors in model-scale UAV design I've seen people make is trying to design the craft from scratch only to discover that their control surfaces are poorly sized, the thing is dynamically unstable, and it requires hand-made spare parts after every flight.

I think an ideal platform for a UAV like you describe would be a foam flying wing with maybe a 3-4 foot wingspan. The flying wing design would at least in theory allow you to decouple some equations which would be difficult to do in traditional fused aircraft and impossible to do in helicopters. Also, unibody construction makes it easier to land without landing gear. Landing without some pretty complex rangefinding hardware is tough, even for a computer system. Doing a skid landing on that huge wing surface with a rear-facing prop will add some margin of error to your landing sequence. If possible, get an ARF (Almost Ready to Fly) model. They come with airframe, power system, and sometimes all the servos. All you need to add is the radio equipment (I assume you are going to have a manual override backup. No, really. You're going to want a manual override.). Expanded polypropylene foam is actually more durable than a lot of people give it credit for, and replacement parts for these aircraft are easy to find.

Everything I've read from people knowledgeable in this matter say helicopters are more difficult because they are naturally unstable where as most airplanes are naturally stable. This means the feedback control systems for helicopters is more difficult.

The forums on the diydrones website (same website that this slashdot questions linked) has all the answers to the questions asked. It might take a few hours to search through those forums and understand enough about what you're reading to find the answers, but a few hours on a project like this is chump change.

20 Years ago Martin got an invitation to speak in Washington, where when he arrived he was surprised to find himself speaking to the top airforce brass. At the time he could not work out why-as UAV became more common he found out!

Note that if you live in USA it is illegal to make UAV. Even first person view flying is illegal.

Bullshit.

People build and fly unmanned aerial aircraft all the time. There are weight and altitude limits, but there's no limit against small (say, under 55 lbs) aircraft at low altitudes (say, under 400 ft above ground), flown by radio control viewed from the ground, or from downlink FPV video, or even partial or full autonomy if you can achieve it. Might want to browse the AMA for sanctioned fields, but you don't have to fly at a group-sanctioned nor government-sanctioned location.

I always wonder why they'd still call it a V-for-Vehicle since there's no passengers, but that's another story.

That is not completely true.There may be local or state laws to prohibit personal UAV's in the USA.Just as there are zoning laws for RC planes and choppers.And lets face it, you very well fly a real plane or chopper out of your garage normally.

But there is no National laws or FAA regulations prohibiting small R/C class planes and choppers being setup as UAV's.But I do believe at some point the FAA would get involved in an ultra light size or better UAV.Because now your talking about real safety issues.

What he's describing is more complex than R/C but there won't be much additional regulation to comply with and the "Feds" won't be interested unless he does something that violates the existing laws.

There are no existing laws or regulations that allow UAVs to fly in US airspace. There are, however, specific exemptions for hobby aircraft -- the essential difference under the current regulations is hobby vs commercial. A hobby UAV is allowed, but a commercial UAV is not allowed.

My company designs small UAV helicopters and flight control computers -- technically, we break the law every time we have a flight test. Luckily, the FAA are under a mandate to develop draft regulations in the next 6-9 months that specifically describe categories for allowable UAV flight in the US (and since their funding is dependent on this requirement, you can expect to see new laws very soon). We flew at a recent FAA demo where they were taking notes to draft the new regulations, so the ball is rolling.

Controlled airspace is really easy to avoid. Just don't go more than 600 feet above the ground or within 3 miles of an airport. That will get you around 95% of the controlled airspace. It's all clearly marked on aeronautical charts. Just go to your local airport and ask any local pilot to pull out a sectional chart and explain how your local airspace works to you.

I had intended to build one, but my working budget went from a little something to less than nothing due to job changes. I still keep my eyes open to what can be done though. Right now, it's a mental exercise.

The most important thing to remember is, as a hobby toy, unless you want to get in serious trouble with the FAA, you must follow a few rules. This is probably not all inclusive. It's just what I can think of off the top of my head from my own research. Find a local R/C group, and reference the FAA pages for more information.

2) You must stay out of any airspace that an aircraft may be flying in. That is, stay out of the approach and departure areas of any airport. Someone just got in trouble for this, where they had an R/C airplane with a camera that filmed a commercial airliner flying by. It was several seconds between the time the aircraft passed, and the wake turbulence knocked his R/C plane out of the air, which would imply a decent separation, but still, stay away from aircraft.

If you haven't gone through private pilot flight school, you may not be aware of the airspace restrictions. Stop by a local small airport and ask. There will always be someone with time on their hands that will love to talk to a newbie.

3) It can never leave your sight,

4) You must have control of it at all times. That is, your remote control must be able to override anything it wants to do.

6) Watch the frequencies that you're using. If you're on R/C frequencies and TX power, you're safe, but play nice with other people who may be flying. Don't hog a bunch of frequencies because you need them for additional controls. If you're working with other frequencies, check the licensing on those. You don't want to piss off the FCC too.

Now I'll go into the territory of ignoring FAA and FCC rules. Don't do it. Don't get caught doing it. Don't tell random strangers that you're doing it. Sure as hell don't post youtube videos of it, because you'll have feds in your livingroom with a no-knock warrant and a one way ticket for you to Southeastern Cuba.

For mine, I looked at a variety of options. If you search around enough, you'll find people mid-sized R/C airplanes (say about a 3' wingspan) with embedded PC's to do their dirty work. I didn't find this totally practical both from the OS standpoint and the interfaces. I want lots and lots of standard interfaces, and I want flexability to use anything I can. I intended to use a small x86 platform machine, running from a flash card (SD/MMC/CF). Delicate parts will get broken quick. Embedded or x86, you'll probably want several onboard to handle different functions. They'd need to be networked together so you can exchange data. For example, one reading your sensors, one to control the servos, one for comms, etc, etc.

I wanted to have the ability to carry at least a couple camcorders, and USB webcams. Every ounce of weight you add means you need the aircraft to support it. That means it needs a good amount of lift and thrust.

I'm assuming you've flown before. If you haven't, go to a local small airport and go for your private pilots license. That will include both ground school (the book work on how things work), and flight (actually working an aircraft). To program an aircraft for perfect conditions is one thing. Making it takeoff, fly, and land in less than ideal conditions is another. What happens if the wind picks up, and you have to slip during your landing? If you haven't programmed for it, either you'll end up way off course if tracking to a GPS coordinate, or you'll get blown way off of the field, probably into something less tha

The difference between RC aircraft and a UAV is that with an RC aircraft someone is flying it in a wide open area where they can see it from the ground and steer it away from hitting anyone or anything. You can't say that for a UAV unless you have a bunch of high resolution cameras sending video back to you in real time. That would make it pretty heavy. Above certain surprisingly low weight limits, you'll need to coordinate your activities with air traffic control. Chances are that most cities are covered with Class B or Class C airspace; so, yes, there will be an air traffic controller to coordinate with.

This issue has come up before from police departments trying to use military class UAV gear for aerial surveillance in urban areas. They want to do this because it is much cheaper to operate than a helicopter. The problem is that they need to reserve large swaths of airspace and they need to have emergency landing areas where the UAV can head to if it fails. In an urban area, there simply aren't many places to put something like this on the ground safely.

Furthermore, if your UAV fails for any reason you could be held liable for millions. These things may look like scale models, but they sure don't fly at scale model speeds. Ten pounds of UAV flying at a relatively slow speed of 100 MPH could cause significant damage or injury. You get extra points if it's on fire. Think long and hard about where you'll be flying this thing.

Oh and one other thing: The good folk at DHS are telling the FAA to look in to model RC aircraft and licensing them because they think it could be used for all sorts of nefarious deeds. Personally, I think that's just plain stupid, but stupidity hasn't stopped DHS/TSA before.